Syntax I

In response to a question about the Patient theta role in class, I mentioned that we are not going to differentiate Themes and Patients, but just call both of them Themes. This is because, even if we can come up with a distinct definition of each, the syntax treats them in the same way. (A quick Google search on “theme patient theta” confirms that pretty much the only time “Theme” and “Patient” appear on the web, it’s either in the string “Theme/Patient” or the string “Patient/Theme”, sometimes “Theme (Patient)”).

The standard definition of Theme/Patient is that it is the “player” in the sentence that undergoes the action, or is affected by the action. But, this is a pretty loose definition, it doesn’t cover all cases.

Suppose that Horton hears a Who. (If that reference is lost on you, a “Who” is in this case a very small sentient species that, in the Dr. Suess children’s story of the same name, caught the attention of an elephant named Horton.) Horton is the Experiencer, and a Who is the Theme—yet the Who is certainly not materially affected by this occurrence. One might say similar things about singing a song, reading a book, copying a DVD.

In general, the idea that the Theme is the thing “affected” can really only serve as a heuristic, not a definition. When something is affected, it will be the Theme, but other things are Themes too. In fact, it might be best to think of Theme as being the role that a participant plays when it doesn’t play a more specific role like Agent, Experiencer, Goal, or Instrument.

We also need to be a bit careful to interpret things like “cause” fairly narrowly. It might be that hearing a particular song causes you to burst into tears. But in the sentence “You heard that song”, that song is still a Theme. The reason, intuitively, is that this sentence doesn’t mean the same thing as “That song made you burst into tears.” It’s just that in this very specific context, it is true whenever “You heard that song” is true. But they are different sentences (they express different propositions), because there could be a context where one is true and the other is false. So, when we determine the theta role, it’s based (in some sense) on the literal meaning of a sentence, and not on any kind of implication or implicature that the sentence might convey. Or, to return to the previous example, even if the Who is shouting, as a result of which Horton heard the Who, the Who is still the theme of heard. It would be the Agent of “The Who shouted”, but that’s a different sentence.

Defining theta roles in a satisfactory way is quite difficult to do, most of syntax proceeds with heuristics and a “we know them when we see them” approach. Subjects are generally Agents or Experiencers (but not always, as with unaccusative verbs like fall or passive verbs such as that in “The Who was heard.”). Objects are generally Themes. Instruments are generally prepositional phrases with with.

It’s unlikely that this helped clarify how to define theta roles, but with luck it may have at least clarified that the situation is a bit murky with respect to determining the theta role an argument gets.